Really?Are you implying that it's not really laughter at all - but only "consistent" with laughter?

Why not just ask, "Why do we laugh when we find something amusing?"

I needed to be more precise than that. With that sequence of sentences, I'm wasn't so much curious about why we laugh as I am about why laughter is universally expressed in the particular way that it is. What, in our evolutionary past, was accomplished by the involuntary vocalization of a succession of the syllable "ha" (or something very much like it)? I'm sure its related to the also universal emotionally communicative phenomena of facial expressions, but that purpose is pretty self evident.

Just in the interests of clarity, I'm not trying to sound smart or superior or, really, anything. I'm just putting these things out there.